Crucible for alumino-thermic processes



ltatented Aug. llll.,. i925...

l .ea.sr ll JERSEY.

Application filed January 192.4. Serial N0.'687,762.

To all whom may concern:

Be it known that I, HERMANN SCHULTZ, a citizen of Germany, residing atBerlin, Lankwitz, Germany, and State of Prussia, have invented certainnew and useful Improvements in Crucibles for Alumino-Thermic Processes,of which the following is a specification.

My invention relates to certain improvements in crucibles for.alumino-thermic proccsses.

The crucibles generally used for aluminothermic processes consists of ashell made of thin sheet iron having a thick lining of refractorymaterial, such as burned magnesia or the like. These crucibles have ashort life because their inner lining is worn out by the excessivelyhigh temperature of the molten mass.

My invention has for its object the provision of a crucible foralumino-thermic processes which is of maximum durability. To this endthe crucible consists in the main of a material of high conductivity forheat, such as copper, bronze, steel, cast iron and the like, and itswall is of such thickness that it has a high capacity for heat. Theeffect is the following:

The liquid mass which is produced by the alumino-thermic processesconsists of a metal and a slag (corundtrm) Owing to its lower specificgravity the slag ascends from all parts to the top of the molten massand on the way covers the inner surface of the crucible, where it ispartly solidified into an adherent thin lining. The remelting of thelatter is prevented by the great conductivity and capacity for heatpossessed by the crucible, so that this lining protects the metallicwall against corrosion by the molten slag and the alumino-genetic metalduring the whole process.

In designing a crucible of the character indicated, it is necessary toprovide suflicient thickness of the metal walls as to enable the heat ofthe reaction to be conducted away from the inner surface of the wallrapidly enough to prevent such inner surface being actually melted and,with such a crucible, there is absolutely no need for a lining of anykind, except the slag lining that is formed durin the reaction. Themaintenance of a re atively cool inner surface of the crucible wall, dueto the dissipation of.

heat generated in the reaction mass within.

the crucible. No hard and fast rule to determine the thickness of thecrucible walls can be made, but a more or less general rule is that thethickness of the crucible walls is such as to provide suflicient metalto conduct away enough heat to prevent melting or fusion of the innersurface of the wall through the nonconducting slag coatin formed in thereaction and deposited on said surface. As a general proposition, it isdesirable to make the walls of the crucible a little thicker than theapplication of this general rule would require.

It is not necessary to remove this lining at the beginning of a newprocess, consequently the crucible may be used continually. Thealumino-thermic mixture with which the crucible is refilled will thenabsorb the heat accumulated in the thick wall.

The crucible may also be provided in advance with a thin lining ofrefractory material all over the whole of its inner surface or only inits lower part, for instance up to the level of the liquid metal.

In the drawing, Figs. 1 and 2 are vertical sections through cruciblesembodying my. in-

vention. Similar letters of reference designate corresponding parts inboth the figures. A represents the metallic wall of the crucible, B aliner of burned magnesia in the discharge outlet, made interchangeableto provide for wear and tear, and C a thin lining of refractory materialin the lower part of the inner metallic wall.

What I claim is: 1. A. receptacle for use in effecting the reduction ofmetals by means of metallic reducing agents comprising a metal crucibleof sufficient wall thickness to chill on its inner surface-a thin layerof slag produced by the reaction.

2. A receptacle for use in effecting exothermic reactions comprising aninitially having a, lining of slag produced by the reunlined metalcrucible of sufficient Wall action. thickness to chill on its innersurface a thin In testimony whereof I afiix my signature layerAof slagpr(1 dufced by the r&action. in presence of two witnesses,

receptace or use in e ectingexo- 'thermic reactions comprising ametallic HERMANN SOHULIZ crucible of sufficient wall thickness to conveyWitnesses away suflicieni; of the heat of reaction to pre- WLAD Ennmzs,vent fusion of its inner surface, said. crucible Roam AUSPAOE

